There are a wide range of analytical operations that may benefit from the ability to analyze the reaction of individual molecules or a relatively small numbers of molecules. A number of approaches have been described for providing these sparsely populated reaction mixtures. For example, in the field of nucleic acid sequence determination, a number of researchers have proposed single molecule or low copy number approaches to obtaining sequence information in conjunction with the template dependent synthesis of nucleic acids by the action of polymerase enzymes.
The various different approaches to these sequencing technologies offer different methods of monitoring only one or a few synthesis reactions at a time. For example, in some cases, the reaction mixture is apportioned into droplets that include low levels of reactants. In other applications, certain reagents are immobilized onto bead or planar surfaces such that they may be monitored without interference from other reaction components in solution. In still another approach, optical confinement techniques have been used to ascertain signal information only from a relatively small number of reactions, e.g., a single molecule, within an optically confined area.
For arrays of optical confinements it can be desirable to have different characteristic properties on various different portions of the surfaces of the optical confinement structures. For example, different surface properties for portions of the surfaces within the observation regions and outside of the observation regions of the optical confinements. Notwithstanding the availability of the above-described techniques, there are instances where greater selectivity of reaction components for analysis would be desirable. The present invention meets these and a variety of needs.